We aimed to assess the effects of GLP-1 agonists on HbA1c, weight, and C-peptide in patients with T1DM with obesity/overweight and normal weight.<h4>Methods</h4>We searched PubMed, Web of Science, Cochrane Library, and Google Scholar from inception up to October 30, 2025. This evidence concerns the gene GCG and type 1 diabetes mellitus.